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P928 53:20 NON-CIRCULATIN
Vol. 53, No.
93-284 0EC011993
20 October 4, 1993
Prevention and Control of Influenza: Vaccines
Recommendations of the Advisory Committee
on Immunization Practices (ACIP)
These recommendations update information on the vaccine available for controlling influenza dur-
ing the 1993-94 influenza season (superseding A4MWR 1992; 41 (No. RR-9):1-17.) The principal
changes include information about + the influenza strains in the trivalent vaccine for 1993-94, +
the effectiveness of influenza vaccine, and + side effects and adverse reactions.
Introduction
Influenza A or B viral infections account for
substantial upper respiratory morbidity
everyfall, winter, and early spring. For opti-
mal prevention and control of influenza,
TDH recommends that vaccination cam-
paigns should be imple-
mented before the 1993-94
influenz a season gets un-
derway inthe fourth quar-
ter of this year. This report
provides vaccination
guidelines for the 1993-94
influenza season and ex-
plains why influenza vac-
cine must be administered
certain groups of people.
annually to
Influenza A viruses are classified into
subtypes based on the antigenic character-
istics of two surface antigens: hemaggluti-
nin (H) and neuraminidase (N). Three
subtypes of hemagglutinin (H1, H2, H3)
and two subtypes of neuraminidase (N1,
N2) associated with epidemic disease have
been identified. Immunity to these anti-
gens, especially to hemagglutinin, reduces
both the likelihood of infection and the se-
verity of disease if infection occurs. Infec-
tion with a virus of one subtype, however,
confers little or no protection against vi-
ruses of other subtypes. Moreover,
influenz? viruses can alter the antigenic
properties of their surface proteins in re-
sponse to increasing levels of immunity in
the population. Over time, antigenic varia-
tion (antigenic drift) within a subtype may
be so extreme that infection or vaccination
with one strain may not induce immunity
to distantly related strains
tine for the of the same subtype. Al-
ludes the fol- though influenza B viruses
s: influenza have demonstrated more
e (HINJ), influ- antigenic stability than in-
/92-like fluenza A viruses, anti-
nza B/ genic variation occurs for
e. B viruses as well. Because
' new variants of influenza
virus emerge every year around the world,
the composition of the influenza vaccine
must be modified annually.
Why Vaccinate Against Influenza?
Although influenza usually is an acute, self-
limiting upper respiratory infection, it may be
complicated by primary influenza pneumonia
or secondary bacterial pneumonia, which
Continued cF
Texas Department
I
of Health
U OF NT DEP. LIBRARIES 76203
TEXAS STATE
DOCUMENTS COLLECTION
The influenza vacc
1993-94 season inc
lowing component
A/Texas/36/91-lik
enza A/Beijing/329
(H3N2), and influx
Panama/45/90-lik
Also in this issue:
FDA Safety Alert Hazards of Volume
Ventilators and Heater Humidifiers
Vaccine-Preventable Disease Update
